This part is a kind of semiconductor called 1N4008.
Function of this product has (1N4001 - 1N4008) General Purpose Plastic Rectifiers.
Manufacturers : LRC
Image and pinout :

Some of the text within the PDF file :
1N4001 thru 1N4008 General Purpose Plastic Rectifiers Reverse Voltage 50 to 1200V Forward Current 1.0A Feature * Plastic package has Underwriters Laboratories Flammability Classification 94V-0 * Construction utilizes void-free molded plastic technique * Low reverse leakage * High forward surge capability * Diffused junction * High temperature soldering guaranteed: 260°C/10 seconds * 0.375" (9.5mm) lead length, 5 lbs. (2.3kg) tension Mechanical Data Case: JEDEC DO-41, molded plastic body Terminals: Plated axial leads, solderable per MIL-STD-750, Method 2026 Polarity: Color band denotes cathode end Mounting Position: Any Weight: 0.011 oz., 0.284 g Handling precaution:None Parameter Symbol device marking code Maximum repetitive peak reverse voltage Maximum RSM voltage Maximum DC blocking vo [ ... ]